In some ways, despite competent writing, this book plodded along for far too long. Maud, the main character, goes through countless reiterations, variations and explanations of "Elizabeth is missing". But the plodding repetition also makes up the main emotional impact of the story: it's a constant reminder of how Maud is utterly trapped by her failing mind and faulty memory. She travels an endless, frustrating and frightening cycle of remembering, misremembering, and forgetting both her past and her present.
There was a mystery component of the plot as well, and it was resolved, somewhat predictably, by book's end, but it's Maud and the haunting portrayal of her diminished life that will stay with me for quite a while.